function newPopupWindow(file, width, height) {
    var msgWindow=open(file,'popup','resizable=yes,scrollbars=yes,width=' + width + ',height=' + height);
    if (msgWindow.opener == null) msgWindow.opener = self;
}

function showPicture(url) {
    newPopupWindow("picture-viewer.jsp?image=" + escape(url), 640, 480);
}